1. Technical Field
The present disclosure relates to a wireless power transmission module. In particular, the present disclosure relates to a wireless power transmission module operable in a magnetic resonance method, a magnetic field shielding unit for a magnetic resonance based wireless power transmission and a portable device including the same, which can block an influence of a magnetic field on components of a portable terminal or its user when a wireless power signal is transmitted and received in the magnetic resonance method, minimize or prevent disturbance to transmission and reception of power signals due to neighboring conductors, and significantly increase efficiency of the magnetic resonance based wireless power transmission by improving characteristics of a radiator.
2. Discussion of the Related Art
Wireless charging technology of portable electronic devices such as mobile phones, personal digital assistants (PDAs), iPads, notebook computers, and tablet PCs is newly emerging. The new wireless charging (WLC) technology enables a portable electronic device to charge a battery by directly transferring power to a portable electronic device without using a power line. Recently, portable electronic devices adopting this technology are increasing. The wireless charging may be classified into a magnetic induction method, and a magnetic resonance method, or classified into a power matters alliance (PMA) standard method and a Qi standard method depending on a method of detecting the wireless power reception module coming close to the wireless power transmission module.
The magnetic induction method and the magnetic resonance method use the magnetic field and are the same technologies in that these generate an electromagnetic field by using coils and transfer the electric power through the electromagnetic field. However, the magnetic induction method is different from the magnetic resonance method in that the magnetic induction method uses an electromagnetic induction phenomenon between coils whereas the magnetic resonance method uses a magnetic resonance phenomenon between the coils. Further, the operating frequencies of the two methods are different from each other. The magnetic induction method is based on a principle in which the magnetic field generated from a primary coil induces a current in a secondary coil to supply energy when the coils are overlapped with each other. The magnetic resonance method is based on a principle that when a magnetic field having a resonant frequency is generated from the wireless power transmission module, the magnetic field is received by a receiving radiator of a wireless power receiving module designed to resonate at the same frequency as the resonance frequency to generate current and supply energy. It is characterized in that the power can be transmitted without direct contact with a charging mat. The magnetic resonance method is basically similar to the magnetic induction method in that the current is converted into the magnetic field through the coil, but different from the magnetic induction method in that the power is transmitted via the converted magnetic field of the resonance frequency over a long distance. In addition, the magnetic resonance method needs a configuration of the wireless power transmission module and the wireless power reception module which include capacitors and coils, so that resonance occurs in a predetermined frequency band and wireless power transmission is performed.
Here, the magnetic resonance method, when the conductors such as the battery, various electronic parts, metal case, and the like are disposed around the radiator of the wireless power transmission module and/or the wireless power reception module, transmitting and receiving a magnetic field having a predetermined operating frequency may be hindered, and as a result, the wireless power transmission operating in magnetic resonance may be blocked or the transmission/reception distance of the wireless power signal may be significantly shortened.
Accordingly, it is required to develop a wireless power transmission module capable of increasing the wireless power transmission distance based on the magnetic resonance method and improving the efficiency even when the conductors are disposed adjacent to the wireless power transmission module.